Selective separation of main flavonoids by combinational use of ionic liquid-loaded microcapsules from crude extract of Tartary buckwheat

Abstract

For selective adsorption of main flavonoids from crude Tartary buckwheat extract (rutin, 0.021 mg/mL; quercetin, 0.030 mg/mL; and kaempferol, 0.011 mg/mL), new ionic liquid-based sorbents were successfully prepared by encapsulating [Bmim]Br and [Bmim]Pro in regular spherical non-magnetic and magnetic microcapsules with polysulfone content of 8%, respectively. After appropriate loading process, the microcapsules were comprehensively characterized by infrared spectroscopy, thermogravimetry analysis and scanning electron microscopy. Then the separation strategy was designed to separate rutin and quercetin from kaempferol by combinational use of two kinds of IL-loaded microcapsules (ILLMs). The effects of solid–liquid ratio of ILLMs and extract, pH, time and adsorption temperature were all investigated. The experimental data fit well with the quasi-second-order kinetics model and Langmuir model. After desorption, target flavonoids were well recovered and the ILLMs showed good stability. As the result, a new IL-based separation technology for main flavonoids from food crop was developed for the first time.